Thanks to recent commits from Wayne, you can now pass a build flag when install jruby with rvm and it will build jruby instead of downloading a prebuilt copy. Make sure you
rvm get head && rvm reload first. Then we can install jruby with 1.9 mode as the default:
rvm install jruby -C -Djruby.default.ruby.version=1.9
And if you want to use jruby-head:
rvm install jruby-head -C -Djruby.default.ruby.version=1.9
I had always wondered why when I installed jruby using rvm it always built something called Nailgun but I never bothered to search about it.
That was a mistake.
Nailgun is an amazing idea that greatly speeds up the start up time of the JVM and subsequently: jruby.
$ time jruby -e ''
$ time jruby --ng -e ''
As you can see, nailgun reduced the start up time for jruby by 500%. Now you may be asking "How do I get started using nailgun?". Well, if you are using rvm then all you need to do is enable the
after_use_jruby hook which will start up a nailgun server for you.
chmod +x "$rvm_hooks_path/after_use" "$rvm_hooks_path/after_use_jruby"
And that's all you need to do.
rvm jruby or
rvm use jruby will now start up a nailgun server if there isn't one running and it set the
--ng switch for all jruby runs.
If you aren't using rvm, you will have to compile nailgun and start up a nailgun server with
jruby --ng-server. Now whenever you run jruby you just add the
--ng switch and it will use the nailgun server. You may want to
export JRUBY_OPTS="--ng" to set the switch for all jruby runs.